In order for children to be as safe as possible in the car these recommendations should be followed:
Birth to AT LEAST age 2: rear facing in an infant or convertible carseat
AT LEAST age 2 to age 6: forward facing in a convertible or combination seat with a 5 pt harness and top tether
Age 6 up to age 12: In a booster seat as long as the child fits. Your child must pass the 5 step test to sit safely in just a seat belt
Over 13: In a seat belt anywhere in the car (backseat is always preferred if available)
The 5 Step Test:
1. Does the child sit all the way back against the auto seat?
2.) Do the child’s knees bend comfortably at the edge of the auto seat?
3.) Does the belt cross the shoulder between the neck and arm?
4.) Is the lap belt as low as possible, touching the thighs?
5.) Can the child stay seated like this for the whole trip?
3.5 yo twins rear facing in a Diono Radian RXT